Publications

The Small-Scale Seal Performance Tests, Series C, a set of in situ experiments conducted at the Waste Isolation Pilot Plant, are designed to evaluate the performance of various seal materials emplaced in large (0.9-m-diameter) boreholes. This report documents the results of fluid (brine) flow testing and water and clay content analyses performed on one emplaced seal comprised of 100% salt blocks and 50%/50% crushed salt/bentonite blocks and disassembled after nearly three years of brine injection testing. Results from the water content analyses of 212 samples taken from within this seal show uniform water content throughout the 50%/50% salt/bentonite blocks with saturations about 100%. Clay content analyses from the 100% salt endcaps of the seal show a background clay content of about 1% by weight uniformly distributed, with the exception of samples taken at the base of the seal at the borehole wall interface. These samples show clay contents up to 3% by weight, which suggests some bentonite may have migrated under pressure to that interface. Results of the brine-flow testing show that the permeability to brine for this seal was about 2 to 3 {times} 10{sup {minus}4} darcy (2 to 3 {times} 10{sup {minus}16} m{sup 2}).

This report documents the state of the art in experimental and theoretical techniques for determining reaction mechanisms and chemical kinetics of heterogeneous reactions relevant to the chemical vapor deposition of semiconductor materials. It summarizes the most common ultra-high vacuum experimental techniques that are used and the types of rate information available from each. Several case studies of specific chemical systems relevant to the microelectronics industry are described. Theoretical methods for calculating heterogeneous reaction rate constants are also summarized.

A new technology called the In Situ Permeable Flow Sensor has been developed at Sandia National Laboratories. These sensors use a thermal perturbation technique to directly measure the direction and magnitude of the full three dimensional groundwater flow velocity vector in unconsolidated, saturated, porous media. The velocity measured is an average value characteristic of an approximately 1 cubic meter volume of the subsurface. During a test at the Savannah River Site in South Carolina, two flow sensors were deployed in a confined aquifer in close proximity to a well which was screened over the entire vertical extent of the aquifer and the well was pumped at four different pumping rates. In this situation horizontal flow which is radially directed toward the pumping well is expected. The flow sensors measured horizontal flow which was directed toward the pumping well, within the uncertainty in the measurements. The observed magnitude of the horizontal component of the flow velocity increased linearly with pumping rate, as predicted by theoretical considerations. The measured horizontal component of the flow velocity differed from the predicted flow velocity, which was calculated with the assumptions that the hydraulic properties of the aquifer were radially homogeneous and isotropic, by less than a factor of two. Drawdown data obtained from other wells near the pumping well during the pump test indicate that the hydraulic properties of the aquifer are probably not radially homogeneous but the effect of the inhomogeneity on the flow velocity field around the pumping well was not modeled because the degree and distribution of the inhomogeneity are unknown. Grain size analysis of core samples from wells in the area were used to estimate the vertical distribution of hydraulic conductivity.

After a series of meetings held in response to an Unsatisfactory Report on the use of vacuum cleaners, an experimental study of commonly available vacuum cleaners was conducted. The object of the study was to evaluate the effectiveness of the cleaners as electrostatic generators. The electrical charges generated by the machine can inadvertently be transferred in normal operations to electroexplosive devices (EEDs), thereby creating a potentially hazardous situation. In the course of this study, it was determined that many inexpensive commercial cleaners could be used safely providing certain modifications were made. Details of the required modification and rationale for the modification are presented in this report.

The Integrated Engineering Information Technology (IEIT) project is providing a comprehensive, easy-to-use computer network solution or communicating with coworkers both inside and outside Sandia National Laboratories. IEIT capabilities include computer networking, electronic mail, mechanical design, and data management. These network-based tools have one fundamental purpose: to help create a concurrent engineering environment that will enable Sandia organizations to excel in today`s increasingly competitive business environment.

SPH (Smoothed Particle Hydrodynamics) is a gridless Lagrangian technique which is appealing as a possible alternative to numerical techniques currently used to analyze high deformation impulsive loading events. In the present study, the SPH algorithm has been subjected to detailed testing and analysis to determine its applicability in the field of solid dynamics. An important result of the work is a rigorous von Neumann stability analysis which provides a simple criterion for the stability or instability of the method in terms of the stress state and the second derivative of the kernel function. Instability, which typically occurs only for solids in tension, results not from the numerical time integration algorithm, but because the SPH algorithm creates an effective stress with a negative modulus. The analysis provides insight into possible methods for removing the instability. Also, SPH has been coupled into the transient dynamics finite element code PRONTO, and a weighted residual derivation of the SPH equations has been obtained.

This report documents the reentry safety analyses conducted for the TOPAZ II Nuclear Electric Propulsion Space Test Program (NEPSTP). Scoping calculations were performed on the reentry aerothermal breakup and ground footprint of reactor core debris. The calculations were used to assess the risks associated with radiologically cold reentry accidents and to determine if constraints should be placed on the core configuration for such accidents. Three risk factors were considered: inadvertent criticality upon reentry impact, atmospheric dispersal of U-235 fuel, and the Special Nuclear Material Safeguards risks. Results indicate that the risks associated with cold reentry are very low regardless of the core configuration. Core configuration constraints were therefore not established for radiologically cold reentry accidents.

The US Department of Energy (DOE) is responsible for management and disposal of large quantities of depleted uranium (DU) in the DOE complex. Viable economic options for the use and eventual disposal of the material are needed. One possible option is the use of DU as shielding material for vitrified Defense High-Level Waste (DHLW) storage, transportation, and disposal packages. Use of DU as a shielding material provides the potential benefit of disposing of significant quantities of DU during the DHLW storage and disposal process. Two DU package concepts have been developed by Sandia National Laboratories. The first concept is the Storage/Disposal plus Transportation (S/D+T) package. The S/D+T package consists of two major components: a storage/disposal (S/D) container and a transportation overpack. The second concept is the S/D/T package which is an integral storage, transportation, and disposal package. The package concept considered in this analysis is the S/D+T package with seven DHLW waste canisters. The S/D+T package provides shielding and containment for the DHLW waste canisters. The S/D container is intended to be used as an on-site storage and repository disposal container. In this analysis, the S/D container is constructed from a combination of stainless steel and DU. Other material combinations, such as mild steel and DU, are potential candidates. The transportation overpack is used to transport the S/D containers to a final geological repository and is not included in this analysis.

Laboratory measurements of single-phase, steady-state permeability of porous rock are important for a number of different applications. The oil and gas industry uses permeability data as a key indicator of the producability of a hydrocarbon reservoir; effective containment of large volumes of oil in underground salt caverns is directly dependent upon the permeability of the adjacent cavern walls; and safe, long term underground isolation of radioactive and hazardous waste is contingent upon the flow and transport characteristics of the surrounding geologic formations. An alternative method for measuring single-phase, steady-state permeability of porous rock is presented. The use of troublesome and expensive mass flow meters is eliminated and replaced with a bridge configuration of flow resistors. Permeability values can be determined directly from differential pressures across the bridge network, resulting in potentially significant cost savings and simplification for conducting these types of measurements. Results from the bridge permeameter are compared with results obtained using conventional methods.

The purpose of this NUREG is to provide technical information useful for the development of fiber-optic communications and intrusion detection subsystems relevant to physical protection. There are major sections on fiber-optic technology and applications. Other topics include fiber-optic system components and systems engineering. This document also contains a glossary, a list of standards and specifications, and a list of fiber-optic equipment vendors.

This report discusses the testing and evaluation of four commercially available fiber optic intrusion detection systems. The systems were tested under carpet-type matting and in a vaulted ceiling application. This report will focus on nuisance alarm data and intrusion detection results. Tests were conducted in a mobile office building and in a bunker.

Activities involving regulatory implementation of updated source term information were pursued. These activities include the identification of the source term, the identification of the chemical form of iodine in the source term, and the timing of the source term`s entrance into containment. These activities are intended to support a more realistic source term for licensing nuclear power plants than the current TID-14844 source term and current licensing assumptions. MELCOR calculations were performed to support the technical basis for the updated source term. This report presents the results from three MELCOR calculations of nuclear power plant accident sequences and presents comparisons with Source Term code Package (STCP) calculations for the same sequences. The three low-pressure sequences were analyzed to identify the materials which enter containment (source terms) and are available for release to the environment, and to obtain timing of sequence events. The source terms include fission products and other materials such as those generated by core-concrete interactions. All three calculations, for both MELCOR and STCP, analyzed the Surry plant, a pressurized water reactor (PWR) with a subatmospheric containment design.

Geothermal energy is one of the more promising renewable energy technologies because it is environmentally benign and, unlike most renewable energy sources, can provide base power. This report provides an assessment of the research and development (R&D) work underway in geothermal energy in the following countries: Denmark, France, Germany, Italy, Japan, Russia, and the United Kingdom. While the R&D work underway in the US exceeds the R&D efforts of the other countries, the lead is eroding. This erosion is due to reductions in federal government funding for geothermal energy R&D and the decline of the US petroleum industry. This erosion of R&D leadership is hindering commercialization of US geothermal energy products and services. In comparison, the study countries are promoting the commercialization of their geothermal energy products and services. As a result, some of these countries, in particular Japan, will probably have the largest share of the global market for geothermal energy products and services; these products and services being targeted toward the developing countries (the largest market for geothermal energy).

In the past, many optimization schemes for massively parallel computers have attempted to achieve parallel efficiency using one of two methods. In the case of large and expensive objective function calculations, the optimization itself may be run in serial and the objective function calculations parallelized. In contrast, if the objective function calculations are relatively inexpensive and can be performed on a single processor, then the actual optimization routine, itself may be parallelized. In this paper, a scheme based upon the Parallel Direct Search (PDS) technique is presented which allows the objective function calculations to be done on an arbitrarily large number (p2) of processors. If, p, the number of processors available, is greater than or equal to 2p{sub 2} then the optimization may be parallelized as well. This allows for efficient use of computational resources since the objective function calculations can be performed on the number of processors that allow for peak parallel efficiency and then further speedup may be achieved by parallelizing the optimization. Results are presented for an optimization problem which involves the solution of a PDE using a finite-element algorithm as part of the objective function calculation. The optimum number of processors for the finite-element calculations is less than p/2. Thus, the PDS method is also parallelized. Performance comparisons are given for a nCUBE 2 implementation.

The effect of a sidewall thermometry probe on heat transport measurements in liquid 4He very close to the superfluid transition is simulated numerically. The effective thermal position of the probe changes with closeness of approach to the superfluid transition. The radial heat flux induced by the sidewall probe is calculated for specific probe designs. © 1994.

Using Saturn as a driver, we are pursueing both photoresonantly pumped andphotoionization/recombination lasers. Our lasing targets are gas cells with thin windowsthat are pumped by a z pinch 2 cm away radiating 10 TW. In both schemes the lasant and gasfill is neon. We will present evidence for inversion in the sodium/neon photoresonantscheme but we have yet to detect the lasing transition itself. To increase our chances ofmeasuring this line we have introduced potassium into a sodium z-pinch and have eliminatedoxygen from the gas cell windows. We have measured the spatial dependence of ionizationbalance across the gas cell, and this measurement is consistent with propagation of a shockfront across the gas cell target. We have measured the Li-like neon Sf-3d transition toincrease more rapidly with fill pressure than all other measured lines. Based on this resultwe have performed experiments emphasizing the photoionization/recombination laserscheme that use a flat field grazing incidence spectrometer to provide good spatial resolutionof the 4f-3d, 4d-3p, and Sf-3d lines of Li-like neon. We have attempted a gain lengthmeasurement by imaging parallel to a baffle that varies the length of the target illuminated.

This work addressed two major areas concerning joining of advanced borated stainless steels. These areas included the development of a understanding of the physical metallurgy of borated stainless steels and the development of welding processes and post-weld heat treatments for these alloys. Differential thermal analysis experiments were conducted on ten heats of borated stainless steel to determine the transformation temperatures and melting behavior of the alloys. On-heating solidus temperatures were measured for all of the alloys and were used to define the temperatures associated with the fusion line during welding. Isothermal heat treatments designed to evaluate the effects of elevated temperature exposures on the toughness of the borated grades were conducted. These tests were used to determine if significant changes in the microstructure or mechanical properties of weld heat-affected zones (HAZ) occur. Specifically, the tests addressed the solid-state region of the HAZ. The test matrix included a variety of alloy compositions and thermal exposures at temperatures near the on-heating solidus (as determined by the DTA experiments). Welding experiments designed to assess the mechanical properties and microstructure of gas-tungsten arc and electron beam welds were conducted.

We present a theory for transforming the system-theory-based realization models into the corresponding physical coordinate-based structural models. The theory has been implemented into computational procedure and applied to several example problems. Our results show that the present transformation theory yields an objective model basis possessing a unique set of structural parameters from an infinite set of equivalent system realization models. For proportionally damped systems, the transformation directly and systematicaly yields the normal modes and modal damping. Moreover, when nonproportional damping is present, the relative magnitude and phase of the damped mode shapes are separately characterized, and a corrective transformation is then employed to capture the undamped normal modes and nondiagonal modal damping matrix.

MELCOR is a fully integrated, engineering-level computer code, being developed at Sandia National Laboratories for the USNRC. This code models the entire spectrum of severe accident phenomena in a unified framework for both BWRs and PWRs. As part of an ongoing assessment program, the MELCOR computer code has been used to analyze a station blackout transient in Surry, a three-loop Westinghouse PWR. Basecase results obtained with MELCOR 1.8.2 are presented, and compared to earlier results for the same transient calculated using MELCOR 1.8.1. The effects of new models added in MELCOR 1.8.2 (in particular, hydrodynamic interfacial momentum exchange, core debris radial relocation and core material eutectics, CORSOR-Booth fission product release, high-pressure melt ejection and direct containment heating) are investigated individually in sensitivity studies. The progress in reducing numeric effects in MELCOR 1.8.2, compared to MELCOR 1.8.1, is evaluated in both machine-dependency and time-step studies; some remaining sources of numeric dependencies (valve cycling, material relocation and hydrogen burn) are identified.

It is inevitable that sealing and abandonment will someday occur in a SPR cavern or caverns. To gain insight into the long-term behavior of a typical SPR cavern following sealing and abandonment, a suite of mechanical finite-element calculations was performed. The initial analyses predict how quickly and to what extent a cavern pressurizes after it is plugged. The analyses also examine the stability of the cavern as it changes shape due to the excessive pressures generated as the salt creeps and the brine in the cavern thermally expands. These large-scale analyses do not include the details of the plug but assume a good seal is established in the cavern wells. In another series of analyses, the potential for forming a leak at the plug is evaluated. A cement plug, emplaced in the casing seat of a cavern well, is loaded using the predicted brine pressures from the cavern analyses. The plugged casing analyses examine the potential for forming a leak path in and along the interfaces of salt, casing, and cement plug. In the last set of analysis, the dimensional scale of the problem is further reduced to examine a preexisting crack along a casing/salt interface. The cracked interface is assumed to be fluid filled and fully pressurized by the cavern fluids. The analyses address the potential for the fluid path to extend upwards along a plugged casing should an open microannulus surround the casing after it is plugged.

The Intelligent Manufacturing Systems (IMS) Test Case 6 project (Rapid Product Development) was set up to demonstrate rapid product development and 3D measurement techniques where the agencies performing the work were distributed over different countries. Test Case 6 provided a unique opportunity to examine the process by which an application protocol (AP) of the Standard for Exchange of Product Data is prepared. The test case had a well defined scope, the production of simple parts by means of layered manufacturing techniques. The information concerned with this manufacture was similarly well defined, due to the requirement that the information be transmitted among the organizations participating in the test case. STEP is an international standard specifying the data content and format for storage and exchange of product data throughout the product`s life cycle. STEP has been under development since 1984 and is just now emerging as an International Standard. STEP is specified as a series of information models using the EXPRESS computer language. For purposes of data exchange, a mapping to a physical file format is specified. Informally, product data can be defined as all the data about a product which one might wish to save. This definition implies some variation in the amount of data to be saved in any one instance. In the case of Test Case 6, one would certainly wish to save the IGES files describing the part. One may or may not wish to save the manufacturing parameters. While there are many parts of STEP with different purposes, the important series of parts for the purposes of standardizing product data are those dealing with application protocols. An application protocol specifies the details of product data within the context of a single application (in this case, layered manufacturing). Other APs deal with such subjects as configuration-managed solid parts and associated drafting.

A key feature distinguishing robotics from traditional computer science is its connection to the physical world. Robot planning software may use elegant algorithms supported by ironclad analytic proofs, but ultimately nature will decide whether the software output is correct in the sense of accomplishing the task goal. Thus a chief goal of robotics research is to understand and capture this nature in a way that allows algorithmic analysis to produce robust physical results. This is made particularly difficult by the presence of uncertainty, which arises from the inevitable discrepancy between the real task and its idealized computer model. This paper reviews fundamental sets of states, forces, and actions that exist for a broad class of robot manipulation tasks, and ties these sets to past and future approaches to developing robust manipulation planning and execution systems.

The Nevada Test Site (NTS) is one excellent possibility for a laser power beaming site. It is in the low latitudes of the US, is in an exceptionally cloud-free area of the southwest, is already an area of restricted access (which enhances safety considerations), and possesses a highly-skilled technical team with extensive engineering and research capabilities from underground testing of our nation`s nuclear deterrence. The average availability of cloud-free clear line of site to a given point in space is about 84%. With a beaming angle of {plus_minus}60{degree} from the zenith, about 52 geostationary-orbit (GEO) satellites could be accessed continuously from NTS. In addition, the site would provide an average view factor of about 10% for orbital transfer from low earth orbit to GEO. One of the major candidates for a long-duration, high-power laser is a reactor-pumped laser being developed by DOE. The extensive nuclear expertise at NTS makes this site a prime candidate for utilizing the capabilities of a reactor pumped laser for power beaming. The site then could be used for many dual-use roles such as industrial material processing research, defense testing, and removing space debris.

Detailed computational modeling of laser surgery requires treatment of the photoablation of human tissue by high intensity pulses of laser light and the subsequent thermomechanical response of the tissue. Three distinct physical regimes must be considered to accomplish this: (1) the immediate absorption of the laser pulse by the tissue and following tissue ablation, which is dependent upon tissue light absorption characteristics; (2) the near field thermal and mechanical response of the tissue to this laser pulse, and (3) the potential far field (and longer time) mechanical response of witness tissue. Both (2) and (3) are dependent upon accurate constitutive descriptions of the tissue. We will briefly review tissue absorptivity and mechanical behavior, with an emphasis on dynamic loads characteristic of the photoablation process. In this paper our focus will center on the requirements of numerical modeling and the uncertainties of mechanical tissue behavior under photoablation. We will also discuss potential contributions that computational simulations can make in the design of surgical protocols which utilize lasers, for example, in assessing the potential for collateral mechanical damage by laser pulses.

New kinds of semiconductor microcavity lasers are being created by modern semiconductor technologies like molecular beam epitaxy and electron beam lithography. These new microcavities exploit 3-dimensional architectures possible with epitaxial layering and surface patterning. The physical properties of these microcavities are intimately related to the geometry imposed on the semiconductor materials. Among these microcavities are surface-emitting structures which have many useful properties for commercial purposes. This paper reviews the basic physics of these microstructured lasers.